Dataset Information

Identification of Selected Tuna Species in Commercial Products.

ABSTRACT: This study was conducted to develop systems for the identification of four tuna species (skipjack tuna Katsuwonus pelamis, yellowfin tuna Thunnus albacares, bullet tuna Auxis sp. and Atlantic bonito Sarda sp). At first, raw samples of these species and a mix intended as internal control were prepared for the authentication of fish muscle tissue of the genus Thunnus sp., Auxis sp. and Sarda sp. DNA from raw muscle tissue, the mix and samples was extracted with the DNeasy mericon Food Kit (Qiagen GmbH, Hilden, Germany). The concentration and purity of DNA in raw samples were evaluated using a spectrophotometer. Primers and probe sequences were specifically designed to identify the selected species. In addition, primers and a probe for the endogenous 12S rRNA gene were designed to determine the presence of amplifiable fish (especially tuna) DNA in samples. Furthermore, the species specificity of the designed primers and probes was verified in DNA samples of various tuna and bonito species. Limit of detection for the selected species was calculated as well as the coefficient of determination R² and efficiency of real-time PCR testing was determined. To evaluate the developed real-time PCR methods, 70 commercial tuna products were analysed. The results show that mislabelling of fish products can still be encountered and, moreover, the presence of an additional species can be identified.

SUBMITTER: Servusova E

PROVIDER: S-EPMC7924337 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Identification of Selected Tuna Species in Commercial Products.

Servusova Eliska E Piskata Zora Z

Molecules (Basel, Switzerland) 20210220 4

This study was conducted to develop systems for the identification of four tuna species (skipjack tuna Katsuwonus pelamis, yellowfin tuna Thunnus albacares, bullet tuna Auxis sp. and Atlantic bonito Sarda sp). At first, raw samples of these species and a mix intended as internal control were prepared for the authentication of fish muscle tissue of the genus Thunnus sp., Auxis sp. and Sarda sp. DNA from raw muscle tissue, the mix and samples was ex ...[more]

PMID: 33672711

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Project description:BACKGROUND: DNA barcodes are a global standard for species identification and have countless applications in the medical, forensic and alimentary fields, but few barcoding methods work efficiently in samples in which DNA is degraded, e.g. foods and archival specimens. This limits the choice of target regions harbouring a sufficient number of diagnostic polymorphisms. The method described here uses existing PCR and sequencing methodologies to detect mitochondrial DNA polymorphisms in complex matrices such as foods. The reported application allowed the discrimination among 17 fish species of the Scombridae family with high commercial interest such as mackerels, bonitos and tunas which are often present in processed seafood. The approach can be easily upgraded with the release of new genetic diversity information to increase the range of detected species. RESULTS: Cocktail of primers are designed for PCR using publicly available sequences of the target sequence. They are composed of a fixed 5' region and of variable 3' cocktail portions that allow amplification of any member of a group of species of interest. The population of short amplicons is directly sequenced and indexed using primers containing a longer 5' region and the non polymorphic portion of the cocktail portion. A 226 bp region of CytB was selected as target after collection and screening of 148 online sequences; 85 SNPs were found, of which 75 were present in at least two sequences. Primers were also designed for two shorter sub-fragments that could be amplified from highly degraded samples. The test was used on 103 samples of seafood (canned tuna and scomber, tuna salad, tuna sauce) and could successfully detect the presence of different or additional species that were not identified on the labelling of canned tuna, tuna salad and sauce samples. CONCLUSIONS: The described method is largely independent of the degree of degradation of DNA source and can thus be applied to processed seafood. Moreover, the method is highly flexible: publicly available sequence information on mitochondrial genomes are rapidly increasing for most species, facilitating the choice of target sequences and the improvement of resolution of the test. This is particularly important for discrimination of marine and aquaculture species for which genome information is still limited.

Project description:Species of Ganoderma, commonly called reishi (in Japan) or lingzhi (in China), have been used in traditional medicine for thousands of years, and their use has gained interest from pharmaceutical industries in recent years. Globally, the taxonomy of Ganoderma species is chaotic, and the taxon name Ganoderma lucidum has been used for most laccate (shiny) Ganoderma species. However, it is now known that G. lucidum sensu stricto has a limited native distribution in Europe and some parts of China. It is likely that differences in the quality and quantity of medicinally relevant chemicals occur among Ganoderma species. To determine what species are being sold in commercially available products, twenty manufactured products (e.g., pills, tablets, teas, etc.) and seventeen grow your own (GYO) kits labeled as containing G. lucidum were analyzed. DNA was extracted, and the internal transcribed spacer (ITS) region and translation elongation factor 1-alpha (tef1?) were sequenced with specific fungal primers. The majority (93%) of the manufactured reishi products and almost half of the GYO kits were identified as Ganoderma lingzhi. G. lingzhi is native to Asia and is the most widely cultivated and studied taxon for medicinal use. Illumina MiSeq sequencing of the ITS1 region was performed to determine if multiple Ganoderma species were present. None of the manufactured products tested contained G. lucidum sensu stricto, and it was detected in only one GYO kit. G. lingzhi was detected in most products, but other Ganoderma species were also present, including G. applanatum, G. australe, G. gibbosum, G. sessile, and G. sinense. Our results indicate that the content of these products vary and that better labeling is needed to inform consumers before these products are ingested or marketed as medicine. Of the 17 GYO kits tested, 11 kits contained Ganoderma taxa that are not native to the United States. If fruiting bodies of exotic Ganoderma taxa are cultivated, these GYO kits will likely end up in the environment. The effects of these exotic species to natural ecosystems needs investigation.

Dataset Information

Identification of Selected Tuna Species in Commercial Products.

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Identification of Selected Tuna Species in Commercial Products.

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